HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Supplemental Research Data All Versions of this Article: ps.073318308v1 17/3/431    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Henzl, M. T. Articles by Tanner, J. J. Search for Related Content PubMed PubMed Citation Articles by Henzl, M. T. Articles by Tanner, J. J. Social Bookmarking                   What's this?

Solution structure of Ca²⁺-free rat -parvalbumin

¹ Department of Biochemistry, University of Missouri-Columbia, Columbia, Missouri 65211, USA
² Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211, USA

(RECEIVED October 25, 2007; FINAL REVISION October 25, 2007; ACCEPTED November 26, 2007)

Mammals express two parvalbumins—an isoform and a β isoform. In rat, the -parvalbumin (-PV) exhibits superior divalent ion affinity. For example, the standard free energies for Ca²⁺ binding differ by 5.5 kcal/mol in 0.15 M KCl (pH 7.4). High-resolution structures of the Ca²⁺-bound proteins provide little insight into this disparity, prompting a structural analysis of the apo-proteins. A recent analysis of rat β-PV suggested that Ca²⁺ removal provokes substantial conformational changes—reorientation of the C, D, and E helices; reorganization of the hydrophobic core; reduced interdomain contact; and remodeling of the AB domain. The energetic penalty attendant to reversing these changes, it was suggested, could contribute to the attenuated divalent ion-binding signature of that protein. That hypothesis is supported by data presented herein, describing the solution structure and peptide backbone dynamics of Ca²⁺-free rat -PV. In marked contrast to rat β-PV, the apo- and Ca²⁺-loaded forms of the rat isoform are quite similar. Significant structural differences appear to be confined to the loop regions of the molecule. This finding implies that the -PV isoform enjoys elevated divalent ion affinity because the metal ion-binding events do not require major structural rearrangement and the concomitant sacrifice of binding energy.

Keywords: calcium-binding protein; EF-hand protein; parvalbumin; NMR; structure; dynamics

CiteULike

Connotea

Del.icio.us

Digg

Reddit

Technorati